CChkSGFiles.PAGE_INFO struct

Article
01/22/2022

Applies to: Exchange Server 2003 | Exchange Server 2007 | Exchange Server 2010 | Exchange Server 2013

Holds information for an Exchange database page. This structure is used with the ErrCheckDbPages function.

Struct PAGE_INFO  
{
        ULONGulPgno;
        BOOLfPageIsInitialized : 1;
        BOOLfCorrectableError : 1;
        ULONGLONGchecksumActual;
        ULONGLONGchecksumExpected;
        ULONGLONGdbTime;
        ULONGLONGchecksumPageStructure;
        ULONGLONGulFlags;
}

Members

ulPgNo

Unsigned Long. Logical page number of the database page to be checked. This value must be set before calling ErrCheckDbPages. If the application is reading the file based on file offsets, and must therefore map those file offsets to logical page numbers, you will find the PgnoFromFileOffset method useful to determine the value for this field. ErrCheckDbPages does not modify this value.

fPageIsInitialized

Boolean. A value of TRUE indicates that the database page contains data. A value of FALSE indicates that the page contains only zeros. ErrCheckDbPages sets this value.

fCorrectableError

Boolean. A value of TRUE indicates that there was a checksum mismatch detected in the database page, but that it is a correctable error. ErrCheckDbPages sets this value.

checksumActual

Unsigned 64-bit integer. Indicates the checksum value stored in the database for this logical page. ErrCheckDbPages sets this value.

checksumExpected

Unsigned 64-bit integer. This is the expected checksum value that is calculated for the database page; it is set by ErrCheckDbPages. If this value is different from that stored on the database page (that is, the value returned in checksumActual), ErrCheckDbPages will indicate that an error was found on this database page.

dbTime

Unsigned 64-bit integer. ErrCheckDbPages sets this member to the timestamp on the database page.

checksumPageStructure

Unsigned 64-bt integer. ErrCheckDbPages sets this member to the calculated checksum value of the contents of the page excluding data which is unnecessary when determining the logical page equivalence. For example, it is unnecessary to consider the data values in unused database page space. This member is only valid if the checksumActual and checksumExpected values are equal to each other.

ulFlags

Unsigned 64-bit integer. Reserved for future use. The value of this field must be set to 0 (zero) before calling ErrCheckDbPages.

Remarks

When calling the ErrCheckDbPages function, the rgPageInfo parameter is an array of PAGE_INFO structures. There must be one PAGE_INFO structure for each database page to be checked.

The application must set the ulPgno member to the proper value, and must also set the ulFlags member to 0 (zero) before calling ErrCheckDbPages.

Requirements

Exchange Server 2013 only includes a 64-bit version of the CHKSGFILES API.

The account that the application is running under must have read access permissions to the database and log files that are to be checked.

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